I hope someone can help with this issue. A client is sending me videos recorded with iPhone; with dual-channel MONO AAC-LC audio, an average of 89 kbps. It's mono but dual-channel. I'm editing with Premiere Pro, and on export, I choose H.264 with AAC-STEREO. (I guess it does not change anything it's still a mono duplicated in both channels?) But I'm choosing Stereo because I'm also using another short Stereo AAC 192 kbps track in the same project, although 90% of audio in this project is 89 kbps.
The question is:
Should I keep the closest bitrate on export (96kbps) or upsample to 192kbps if I choose Stereo on export, or because of that other audio. Just want to keep best possible quality and not sure if upsampling is beneficial or it could degrade the quality of 89kbps audio?
Export have to be in AAC format, so please don't suggest to convert to another format. Thanks! :)